Hydraulic oil actuators for moving the point blades are known.
A double-acting linear actuator or two linear actuators which are independent and operate oppositely each other are connected to the delivery lines of a hydraulic oil circuit. The hydraulic oil fluid is supplied to the actuators by an electric motor driven pump, which takes the fluid from a reservoir or causes the fluid to flow in a closed circuit with a delivery line and a return line.
In order to achieve the movement from the normal position to the reverse position and vice versa in the supply circuit, valves are provided which are electrically operated and can be switched to connect the delivery end of the circulation pump (i.e., the delivery line of the circuit) in a first condition to the inlet of one of the two actuators (or to one of the two inlets of a double-acting actuator) and in a second condition to the inlet of the other one of the two actuators (or to the other inlet of a double-acting actuator). At the same time, the actuator not supplied by the fluid (or the inlet of the double-acting cylinder not connected to the delivery line) is connected to the intake end of the circulation pump by the return line of the circulation circuit.
A hydraulic oil fluid reservoir draws the fluid and fills the closed circuit, or gathers the hydraulic oil fluid discharged from one or more outlets of the circuit.
The length of time during which the fluid is supplied to the actuators is determined by electrical means such as pressure sensors and/or electric timers or valves or combinations of such means.
In addition to the fact that the construction of the control unit is made more complex and expensive, known solutions providing electrical means for switching the movement direction of the point blades and timing electrical means are relatively unsafe with reference to the high standards required in the railway field and in similar fields.